fabf2

My 2001.5 A4 heater doesn't seem to work properly, and it can get really really cold in the winter.
Last fall I noticed that the air blowing from any of the ports sometimes went cool, then warm then cool etc. In January it went cool and stayed that was until March.
Dealer flushed the heater core 3 times and that seemed to make a difference, but again this fall I get the same oscillating temperature.
But I also noted several g92 ( this is the heater Flap Motor requested position) faults (intermittent short) and the measured value of G92 varies through half its range. This can also be seen in the AC panel codes number 8 and 9.
I suspect that there may be a loose connection or other problem with the sensor that says what the g92 position is.
Does anyone have any familiarity with this kind of problem. Should I expect to see the actual position reading as pretty well stable? (the range is 0 thro 255 and the reading vary from 38 to 255...not stable)
Hope someone can shed some light on this before I freeze.
Thanks

mtroxel

I'm not sure, but I'll watch 8c and 9c on my 99.5 today. Heater runs fine and that might help give you a baseline.

mtroxel

So I left the house at 9:00 to a client's. 38F and sunny, but too early for any solar gain. Cold motor, Climate Control temp set at 70F.

8c Cold coolant, 4 - 5. As coolant warms, it bounces between 5 & 100 till inside car reaches 70F. Then fan speed settles down to two bars, and 8c sits at 2.

9c starts out around 43, then climbs to 81 - 84 range.

I opened some windows to cool the inside of the car, 8c jumps up to 100+ and the fan spools up to warm up the car back up.

Got in car at client's a couple hours later. 48F outside, and the coolant was at 65C. With the shade open on the sunroof and the higher sun, the climate control never blew any heat. So:

8c started at 123, then as the coolant temp rose, it went to 153 range.
9c started at 115, then as the coolant temp rose, it went to 124 range.